Ultrasonic diagnostic device and ultrasonic image generation method

ABSTRACT

An ultrasonic diagnostic device includes: a probe including a plurality of elements that are arranged; a transmission unit that transmits an ultrasonic beam by performing transmission focusing in a first direction from the plurality of elements of the probe; a reception unit that generates element data by processing reception signals output from the plurality of elements of the probe that has received an ultrasonic echo generated by the ultrasonic beam transmitted from the transmission unit; an element data processing unit that generates reflection component removal data by removing a reflection component generated from the first direction from the element data; an image generation unit that generates an ultrasonic image by performing reception focusing for the element data; and a control unit that controls the image generation unit to generate an image signal along a second direction different from the first direction by performing reception focusing in the second direction for the reflection component removal data generated by the element data processing unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/JP2014/060963 filed on Apr. 17, 2014, which claims priority under 35U.S.C. §119(a) to Japanese Patent Application No. 2013-175711 filed onAug. 27, 2013. The above application is hereby expressly incorporated byreference, in its entirety, into the present application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ultrasonic diagnostic device and anultrasonic image generation method, and in particular, to an ultrasonicdiagnostic device and an ultrasonic image generation method forgenerating an ultrasonic image by performing reception focusing in adifferent direction from the transmission direction of an ultrasonicbeam.

2. Description of the Related Art

Conventionally, in the medical field, an ultrasonic diagnostic deviceusing an ultrasonic image has been put into practical use. In general,this kind of ultrasonic diagnostic device generates an ultrasonic imageby transmitting an ultrasonic beam toward a subject from the ultrasonicprobe, receiving an ultrasonic echo from the subject using theultrasonic probe, and electrically processing the reception signal.

In such an ultrasonic diagnostic device, a tomographic image of theinside of the subject located immediately below the probe cannot beobserved in real time. Accordingly, for example, when inserting theneedle to the target location in the subject, an ultrasonic image of theinside of the subject is generated by placing the probe immediatelyabove a target location and the needle is obliquely inserted toward thetarget location from the vicinity of the probe, so that the needle isinserted while checking the position of the needle in the subject on anultrasonic image.

However, in general, the surface of the needle is smooth. Accordingly,an ultrasonic beam having propagated through the subject from the probeis likely to be regularly reflected on the surface of the needle. Inaddition, since the needle is obliquely inserted toward the targetlocation, it may be difficult to visualize the needle by capturing thespecular reflection of the ultrasonic beam transmitted in the normaldirection of the probe in the reception opening of the probe.

Therefore, visualizing the needle by transmitting an ultrasonic beam ina direction perpendicular to the needle instead of the normal directionof the probe and performing reception focusing has been known.

For example, JP2012-213606A discloses an ultrasonic diagnostic devicethat generates a first image by transmitting and receiving an ultrasonicbeam in a first direction perpendicular to the element surface of aprobe for the purpose of tissue imaging, generates a second image groupby transmitting and receiving an ultrasonic beam in a plurality ofsecond directions, which are different from the direction perpendicularto the element surface, for the purpose of needle imaging, generates animage in which a needle is visualized by analyzing the second imagegroup, and combines the image with the first image.

According to the device disclosed in JP2012-213606A, since a directionperpendicular to the needle is included in the plurality of seconddirections, it is possible to generate an ultrasonic image in which theneedle is satisfactorily visualized.

SUMMARY OF THE INVENTION

In the device disclosed in JP2012-213606A, however, since thetransmission of an ultrasonic beam in a first direction for tissueimaging and multiple transmissions of an ultrasonic beam in a seconddirection for needle imaging are required, there has been a problem thatthe frame rate is reduced.

Therefore, for example, a method of generating a tissue image byperforming reception focusing in the normal direction of the probe forreception signals obtained by transmitting ultrasonic beams in thenormal direction of the probe and generating a needle image byperforming reception focusing in a direction perpendicular to the needlehas been devised by the applicant. According to this method, it ispossible to generate both a tissue image and a needle image with onetransmission of ultrasonic beams.

However, since the ultrasonic beam is transmitted in the normaldirection of the probe, both the strength of the ultrasonic wavetransmitted in the direction of the needle from each element of theprobe and the signal strength when each element receives the reflectedwave from the needle are lower than the strength of the ultrasonic wavetransmitted in the normal direction of the probe and the signal strengthwhen the reflected wave is received from the normal direction. As aresult, since the S/N ratio of the image is reduced, there is apossibility that it becomes difficult to visualize the needle clearly.

The present invention has been made in order to solve such aconventional problem, and it is an object of the present invention toprovide an ultrasonic diagnostic device and an ultrasonic imagegeneration method capable of generating a clear ultrasonic image even ifreception focusing is performed in a different direction from thetransmission direction of the ultrasonic beam.

An ultrasonic diagnostic device according to the present inventionincludes: a probe including a plurality of elements that are arranged; atransmission unit that transmits an ultrasonic beam by performingtransmission focusing in a first direction from the plurality ofelements of the probe; a reception unit that generates element data byprocessing reception signals output from the plurality of elements ofthe probe that has received an ultrasonic echo generated by theultrasonic beam transmitted from the transmission unit; an element dataprocessing unit that generates reflection component removal data byremoving a reflection component generated from the first direction fromthe element data; an image generation unit that generates an ultrasonicimage by performing reception focusing for the element data; and acontrol unit that controls the image generation unit to generate animage signal along a second direction different from the first directionby performing reception focusing in the second direction for thereflection component removal data generated by the element dataprocessing unit.

The transmission unit can form at least two focuses at differentpositions in the first direction to sequentially transmit a plurality ofultrasonic beams, and the element data processing unit can be configuredto generate the reflection component removal data from a plurality ofpieces of element data generated by the reception unit corresponding tothe plurality of ultrasonic beams.

In this case, the element data processing unit generates the reflectioncomponent removal data by taking a difference between the plurality ofpieces of element data.

In addition, when taking a difference between the plurality of pieces ofelement data, the element data processing unit can take a differenceafter giving weighting to any one of the plurality of pieces of elementdata or to the plurality of pieces of element data.

The element data processing unit can be configured to generateoverlapping-processed data in which a reflection component generatedfrom the first direction is emphasized by overlapping a predeterminednumber of pieces of element data generated by the reception unit witheach other by phase matching corresponding to the predetermined numberof consecutive scanning lines and generate the reflection componentremoval data using the overlapping-processed data.

In this case, the element data processing unit generates the reflectioncomponent removal data by taking a difference between the element databy the plurality of elements generated by the reception unit and theoverlapping-processed data.

When taking a difference between the element data by the plurality ofelements generated by the reception unit and the overlapping-processeddata, the element data processing unit can take a difference aftergiving weighting to either the element data by the plurality of elementsgenerated by the reception unit or the overlapping-processed data or toboth the element data by the plurality of elements generated by thereception unit and the overlapping-processed data.

The element data processing unit may be configured to generatesimulation data indicating a reflected wave generated from the firstdirection by simulation and generate the reflection component removaldata using the simulation data.

In this case, the element data processing unit generates the reflectioncomponent removal data by taking a difference between the element databy the plurality of elements generated by the reception unit and thesimulation data.

When taking a difference between the element data by the plurality ofelements generated by the reception unit and the simulation data, theelement data processing unit can take a difference after givingweighting to either the element data by the plurality of elementsgenerated by the reception unit or the simulation data or to both theelement data by the plurality elements generated by the reception unitand the simulation data.

It is preferable that the image generation unit includes: a tissue imagegeneration section that generates an image signal for tissue imagingalong the first direction by performing reception focusing in the firstdirection for the element data; and a needle image generation sectionthat generates an image signal for needle imaging along the seconddirection by performing reception focusing in the second direction forthe reflection component removal data.

It is preferable to further include an image combination unit thatcombines the image signal for tissue imaging generated by the tissueimage generation section and the image signal for needle imagingobtained by the needle image generation section. In addition, it ispreferable to include a display unit that displays an image signalobtained by combination of the image combination unit.

In addition, it is also possible to include a display unit that displaysan ultrasonic image generated by the image generation unit.

An ultrasonic image generation method according to the present inventionincludes: transmitting an ultrasonic beam by performing transmissionfocusing in a first direction from a plurality of elements of a probe;generating element data by processing reception signals output from theplurality of elements of the probe that has received an ultrasonic echogenerated by the ultrasonic beam; generating reflection componentremoval data by removing a reflection component generated from the firstdirection from the element data; and generating an ultrasonic imagealong a second direction different from the first direction byperforming reception focusing in the second direction for the reflectioncomponent removal data.

According to the present invention, element data is generated bytransmitting an ultrasonic beam by performing transmission focusing inthe first direction, reflection component removal data is generated byremoving a reflection component generated from the first direction fromthe element data, and an ultrasonic image along the second directiondifferent from the first direction is generated by performing receptionfocusing in the second direction for the reflection component removaldata. Therefore, even if reception focusing is performed in a differentdirection from the transmission direction of the ultrasonic beam, it ispossible to generate a clear ultrasonic image.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the configuration of an ultrasonicdiagnostic device according to a first embodiment of the presentinvention.

FIG. 2 is a diagram showing the configuration of an element dataprocessing unit in the first embodiment.

FIG. 3 is a diagram showing a state of transmission of the ultrasonicwave in the first embodiment.

FIGS. 4A-4C are diagrams schematically showing first element data,second element data, and reflection component removal data that areobtained in the first embodiment, respectively.

FIG. 5 is a flowchart showing the operation in the first embodiment.

FIG. 6 is a diagram showing the configuration of an element dataprocessing unit in a second embodiment.

FIG. 7A is a diagram showing five pieces of element data when a centralelement of a transmission opening is set as a first observed element,FIG. 7B is a diagram showing a delay time of a receiving time for anelement data corresponding to the first observed element, FIG. 7C showsan overlapping-processed data for the element data corresponding to thefirst observed element, FIG. 7D is a diagram showing five pieces ofelement data when an element adjacent to the left side of the centralelement is set as a second observed element, FIG. 7E is a diagramshowing a delay time of a receiving time for an element datacorresponding to the second observed element, FIG. 7F shows anoverlapping-processed data for the element data corresponding to thesecond observed element, FIG. 7G shows an overlapping state for threeconsecutive pieces of element data, and FIG. 7H shows a result ofoverlapping processing in the second embodiment.

FIGS. 8A-8C are diagrams schematically showing element data,overlapping-processed data, and reflection component removal data thatare obtained in the second embodiment, respectively .

FIG. 9 is a flowchart showing the operation in the second embodiment.

FIG. 10 is a diagram showing the configuration of an element dataprocessing unit in a third embodiment.

FIG. 11 is a flowchart showing the operation of simulation processing inthe third embodiment.

FIGS. 12A-12C are diagrams schematically showing element data,simulation data, and reflection component removal data that are obtainedin the third embodiment, respectively.

FIG. 13 is a flowchart showing the operation in the third embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the accompanying diagrams.

First Embodiment

FIG. 1 shows the configuration of an ultrasonic diagnostic deviceaccording to a first embodiment of the present invention. The ultrasonicdiagnostic device includes a probe 1, and a transmission unit 2 and areception unit 3 are connected to the probe 1. A tissue image generationunit 4 and an element data memory 5 are connected in parallel to thereception unit 3, and a needle image generation unit 7 is connected tothe element data memory 5 through an element data processing unit 6. Animage combination unit 8 is connected to the tissue image generationunit 4 and the needle image generation unit 7, and a display unit 10 isconnected to the image combination unit 8 through a display control unit9.

The control unit 11 is connected to the transmission unit 2, thereception unit 3, the tissue image generation unit 4, the element datamemory 5, the element data processing unit 6, the needle imagegeneration unit 7, the image combination unit 8, and the display controlunit 9. An operation unit 12 and a storage unit 13 are connected to thecontrol unit 11.

The tissue image generation unit 4 serves to generate a tissue image ofthe subject, which is located immediately below the probe 1, andincludes a first reception focusing section 21 connected to thereception unit 3 and a detection processing section 22 and an imagememory 23 that are sequentially connected to the first receptionfocusing section 21. The detection processing section 22 and the imagememory 23 are connected to the image combination unit 8.

On the other hand, the needle image generation unit 7 serves to generatean ultrasonic image of a needle inserted into the subject, and has thesame configuration as the tissue image generation unit 4. That is, theneedle image generation unit 7 includes a second reception focusingsection 31 connected to the element data processing unit 6 and adetection processing section 32 and an image memory 33 that aresequentially connected to the second reception focusing section 31, andthe detection processing section 32 and the image memory 33 areconnected to the image combination unit 8.

The probe 1 includes a plurality of elements arranged in aone-dimensional or two-dimensional manner. Each of these elements is anultrasonic transducer, and transmits an ultrasonic wave according to thedriving signal supplied from the transmission unit 2, receives anultrasonic echo from the subject, and outputs a reception signal. Forexample, each ultrasonic transducer is formed by a transducer in whichelectrodes are formed at both ends of the piezoelectric body formed ofpiezoelectric ceramic represented by lead zirconate titanate (PZT), apolymer piezoelectric element represented by polyvinylidene fluoride(PVDF), piezoelectric single crystal represented by lead magnesiumniobate-lead titanate (PMN-PT), or the like, and has an ultrasonic wavetransmitting and receiving surface with a predetermined area.

When a pulsed or continuous-wave voltage is applied to the electrodes ofthe transducer, the piezoelectric body expands and contracts to generatepulsed or continuous-wave ultrasonic waves from each transducer. By acombination of these ultrasonic waves, an ultrasonic beam is formed. Inaddition, the respective transducers expand and contract by receivingthe propagating ultrasonic waves, thereby generating electrical signals.These electrical signals are output as reception signals of theultrasonic waves.

The transmission unit 2 includes a plurality of pulse generators, forexample. Based on a transmission delay pattern selected according to thecontrol signal from the control unit 11, the transmission unit 2 adjuststhe amount of delay of each driving signal so that ultrasonic wavesemitted from the plurality of elements of the probe 1 form an ultrasonicbeam to be transmitted in a first direction, and supplies the adjustedsignals to the plurality of elements. Here, the first direction is setto the normal direction of the element surface of the probe 1.

The reception unit 3 generates digitized element data by amplifying thereception signal output from each element of the probe 1 and performingA/D conversion.

The first reception focusing section 21 of the tissue image generationunit 4 performs reception focusing in the first direction, that is, inthe normal direction of the element surface of the probe 1 by generatingdelay correction data by performing delay correction for the elementdata generated by the reception unit 3 and adding up the pieces of delaycorrection data. Through the reception focusing processing, a sound raysignal for tissue imaging with narrowed focus of the ultrasonic echo isgenerated.

The detection processing section 22 generates a B-mode image signal fortissue imaging by correcting the attenuation due to the distanceaccording to the depth of the reflection position of the ultrasonic wavefor the sound ray signal generated by the first reception focusingsection 21 and then performing envelope detection processing, andoutputs the B-mode image signal to the image combination unit 8 orstores the B-mode image signal in the image memory 23.

The element data memory 5 stores the element data generated by thereception unit 3, and outputs the element data to the element dataprocessing unit 6.

The element data processing unit 6 generates reflection componentremoval data by removing reflection components, which are generated fromthe normal direction of the element surface of the probe 1 that is thefirst direction, from the element data generated by the reception unit3. In the first embodiment, as shown in FIG. 2, the element dataprocessing unit 6 is formed by a difference calculation section 41connected to the element data memory 5.

The second reception focusing section 31 of the needle image generationunit 7 performs reception focusing in a second direction, which isdifferent from the first direction, by generating delay correction databy performing delay correction for the reflection component removal datagenerated by the element data processing unit 6 and adding up the piecesof delay correction data. Here, the second direction is set to adirection perpendicular to the needle inserted into the body of thesubject. Through the reception focusing processing, a sound ray signalfor needle imaging with narrowed focus of the ultrasonic echo isgenerated.

The detection processing section 32 generates a B-mode image signal forneedle imaging by correcting the attenuation due to the distanceaccording to the depth of the reflection position of the ultrasonic wavefor the sound ray signal generated by the second reception focusingsection 31 and then performing envelope detection processing, andoutputs the B-mode image signal to the image combination unit 8 orstores the B-mode image signal in the image memory 33.

The image combination unit 8 converts (raster conversion) the B-modeimage signal for tissue imaging output from the tissue image generationunit 4 and the B-mode image signal for needle imaging output from theneedle image generation unit 5 into image signals according to thenormal television signal scanning method and performs various kinds ofrequired image processing, such as gradation processing, and thencombines the B-mode image signal for tissue imaging and the B-mode imagesignal for needle imaging. The display control unit 9 displays anultrasonic image on the display unit 10 based on the B-mode image signalcombined by the image combination unit 8.

The display unit 10 includes, for example, a display device, such as anLCD, and displays an ultrasonic image under the control of the displaycontrol unit 9.

The control unit 11 controls each unit of the ultrasonic diagnosticdevice based on the instruction input from the operating unit 12 by theoperator.

The operation unit 12 is used when the operator performs an inputoperation, and can be formed by a keyboard, a mouse, a trackball, atouch panel, and the like.

The storage unit 13 stores an operation program and the like, andrecording media, such as a hard disk, a flexible disk, an MO, an MT, aRAM, a CD-ROM, a DVD-ROM, an SD card, a CF card, and a USB memory, or aserver may be used.

The element data processing unit 6, the first reception focusing section21 and the detection processing section 22 of the tissue imagegeneration unit 4, the second reception focusing section 31 and thedetection processing section 32 of the needle image generation unit 7,the image combination unit 8, and the display control unit 9 are formedby using a CPU and an operation program causing the CPU to executevarious kinds of processing. However, these may be formed by usingdigital circuits.

A method of transmitting and receiving an ultrasonic wave in the firstembodiment will be described. As shown in FIG. 3, it is assumed that aneedle N is inserted at an angle θ from the vicinity of the probe 1 in astate in which the probe 1 is in contact with the body surface of asubject S.

First, a first transmission focus F1 is formed at a predetermined depthin the first direction D1 that is the normal direction of the elementsurface of the probe 1, and a first ultrasonic beam is transmittedtoward the first direction D1 by the transmission unit 2. Then, thefirst ultrasonic beam propagates through the subject S with apredetermined spread after converging on the first transmission focusF1.

In this case, a transmission wave toward a reflection point C present inthe first direction D1 through the first transmission focus F1 from theprobe 1 propagates along a path RO parallel to the first direction D1,and a reflected wave from the reflection point C is received by eachelement of the probe 1. In addition, a transmission wave traveling inthe second direction D2 perpendicular to the needle N through the firsttransmission focus F1 from the probe 1 propagates along a path R1, and areflected wave from the surface of the needle N is received by eachelement of the probe 1.

Then, a second transmission focus F2 is formed at a position, which isin the first direction D1 and is deeper than the first transmissionfocus F1, and a second ultrasonic beam is transmitted toward the firstdirection D1 by the transmission unit 2. Then, the second ultrasonicbeam propagates through the subject S with a predetermined spread afterconverging on the second transmission focus F2.

In this case, a transmission wave toward the reflection point C presentin the first direction D1 through the second transmission focus F2 fromthe probe 1 propagates along the same path R0 as the first ultrasonicbeam, and a reflected wave from the reflection point C is received byeach element of the probe 1. On the other hand, a transmission wavetraveling in the second direction D2 perpendicular to the needle Nthrough the second transmission focus F2 from the probe 1 propagatesalong a path R2, and a reflected wave from the surface of the needle Nis received by each element of the probe 1.

By sequentially transmitting the first ultrasonic beam and the secondultrasonic beam for each scanning line as described above while movingthe scanning line in the arrangement direction of the elements of theprobe 1, first element data and second element data are generated by thereception unit 3.

FIGS. 4(A) and 4(B) show the first element data acquired by transmissionof the first ultrasonic beam and the second element data acquired bytransmission of the second ultrasonic beam, respectively. A reflectedwave H1 from the first direction D1 and a reflected wave H2 from theneedle N are included in the first element data. Similarly, thereflected wave H1 from the first direction D1 and the reflected wave H2from the needle N are included in the second element data.

Here, for the reflection point C present in the first direction D1,since the ultrasonic wave propagates by the same propagation lengthalong the same path R0 both when transmitting and receiving the firstultrasonic beam and when transmitting and receiving the secondultrasonic beam, the reflected wave H1 from the first direction D1 ispresent at the same time position (depth position) in the first elementdata and the second element data.

On the other hand, for the needle N, when transmitting and receiving thefirst ultrasonic beam and when transmitting and receiving the secondultrasonic beam, the paths R1 and R2 of the transmission wave aredifferent and the paths of the reflected wave are different.Accordingly, the reflected wave H2 from the needle N is present atdifferent time positions (depth positions) in the first element data andthe second element data.

Therefore, it is possible to remove the reflected wave H1 from the firstdirection D1 while leaving the reflected wave H2 from the needle N bytaking the difference between the first element data and the secondelement data by the difference calculation section 41 that forms theelement data processing unit 6. In this case, both the reflected wave H2from the needle N in the first element data and the reflected wave H2from the needle N in the second element data are left. However, forexample, by removing the reflected wave H2 from the needle N in thesecond element data, reflection component removal data including thereflected wave H2 from the needle N is generated as shown in FIG. 4(C).Alternatively, it is also possible to generate reflection componentremoval data by combining the reflected wave H2 from the needle N in thefirst element data and the reflected wave H2 from the needle N in thesecond element data.

For example, in difference data obtained by taking the differencebetween the first element data and the second element data, a pluralityof straight lines may be extracted by performing Hough conversion. Then,when one straight line and another long straight line parallel to thestraight line are found, one of the straight lines may be removed. Thatis, in the difference data, the difference value of the linear portionto be removed may be replaced with zero. When removing one of thestraight lines, it is preferable to leave a side on which a pattern ofthe similar linear shape is present at the same position of the firstelement data. Since the first element data and the second element dataalso include reflected waves from objects other than the needle, it isneedless to say that the above-described processing may be performedafter performing processing for reducing or smoothing the first elementdata and the second element data.

By performing reception focusing in the second direction D2 for thereflection component removal data, it is possible to generate a needleimage having an excellent S/N ratio without being influenced by thereflected wave H1 from the first direction D1.

As shown in FIG. 3, in the case of a so-called linear type probe inwhich a plurality of elements of the probe 1 are linearly arrayed,normal directions of the respective elements are parallel to each other.Accordingly, it is preferable to set the first direction D1 to thenormal direction. However, in a so-called convex type probe in which aplurality of elements are arrayed in a curved shape, the normaldirections of the respective elements are different. In this case, thefirst direction D1 can be set to the normal direction of each element.

In addition, the second direction D2 does not necessarily need to be setto a direction perpendicular to the needle N, and may be set to adirection toward the needle N rather than the first direction D1, thatis, a direction having an angle close to the right angle with respect tothe needle N rather than the normal direction of each element.

Next, an operation in the first embodiment will be described withreference to the flowchart shown in FIG. 5.

In the first embodiment, it is assumed that a tissue image in the normaldirection of the element surface of the probe 1 and a needle image in adirection perpendicular to the needle N are generated by setting nscanning lines L1 to Ln and performing a scan.

First, in step S1, the scanning line L1 is initialized to L1. In stepS2, for the first scanning line L1, a reception signal is acquired byperforming transmission focusing on the first transmission focus F1 at apredetermined depth in the normal direction of the element surface ofthe probe 1 that is the first direction D1, and the first element datais acquired by the reception unit 3. That is, according to the drivingsignal supplied from the transmission unit 2, transmission focusing isperformed on the first transmission focus F1 from a plurality ofelements that form a transmission opening corresponding to the scanningline L1, and an ultrasonic beam is transmitted. Then, a reception signaloutput from each element, which is obtained by receiving the reflectedwave from the subject, is amplified and digitized by the reception unit3, and is stored in the element data memory 5.

Then, in step S3, for the same first scanning line, transmissionfocusing is performed on the second transmission focus F2, which is inthe first direction D1 and is at a different depth position from thefirst transmission focus F1, and second element data is acquired by thereception unit 3 and is stored in the element data memory 5.

Then, in step S4, it is determined whether or not i=n, that is, it isdetermined whether or not the acquisition of the first element data andthe second element data has been completed for all of the n scanninglines L1 to Ln.

Here, since the value of i is still “1”, the process proceeds to step S5to set the value of i to “2” by increasing the value of i by “1”, andthen the process returns to step S2. Through steps S2 and S3, firstelement data and second element data corresponding to the secondscanning line L2 are acquired, and are stored in the element data memory5.

Similarly, until i=n, the value of i is increased by 1 in a sequentialmanner, and steps S2 and S3 are repeated.

When the acquisition of the first element data and the second elementdata is completed for all of the n scanning lines L1 to Ln as describedabove, the process proceeds to step S6 from step S4. In step S6, thedifference calculation section 41 that forms the element data processingunit 6 calculates a difference between the first element data and thesecond element data for the scanning lines LI to Ln stored in theelement data memory 5, thereby generating reflection component removaldata in which the reflected wave H1 from the first direction D1 has beenremoved. In this case, in the difference calculation, either the firstelement data or the second element data or both the first element dataand the second element data may be weighted to perform a differencecalculation.

Then, in step S7, a needle image is generated by performing receptionfocusing in a direction perpendicular to the needle N, which is thesecond direction D2, for the reflection component removal data generatedby the difference calculation section 41.

That is, the second reception focusing section 31 of the needle imagegeneration unit 7 generates delay correction data by performing delaycorrection for the reflection component removal data so that receptionfocusing is performed in a direction perpendicular to the needle N, andgenerates a sound ray signal for needle imaging by adding up the piecesof delay correction data. The detection processing section 32 generatesa B-mode image signal for needle imaging by performing envelopedetection processing on the sound ray signal, and the B-mode imagesignal for needle imaging is stored in the image memory 33.

In step S8, a tissue image is generated by performing reception focusingin the normal direction of the element surface of the probe 1, which isthe first direction D1, for the first element data regarding thescanning lines L1 to Ln stored in the element data memory 5.

That is, the first reception focusing section 21 of the tissue imagegeneration unit 4 generates delay correction data by performing delaycorrection for each piece of the first element data so that receptionfocusing is performed in the normal direction of the element surface,and generates a sound ray signal for tissue imaging by adding up thepieces of delay correction data. The detection processing section 22generates a B-mode image signal for tissue imaging by performingenvelope detection processing on the sound ray signal, and the B-modeimage signal for tissue imaging is stored in the image memory 23.

Then, in step S9, the B-mode image signal of the tissue image stored inthe image memory 23 of the tissue image generation unit 4 and the B-modeimage signal of the needle image stored in the image memory 33 of theneedle image generation unit 7 are raster-converted by the imagecombination unit 8, and are combined with each other after various kindsof image processing is performed. As a result, a B-mode image signal ofthe display image is generated.

The B-mode image signal of the display image is output to the displaycontrol unit 9 from the image combination unit 8, and an ultrasonicimage in which the tissue image and the needle image are combined isdisplayed on the display unit 10.

The element data processing unit 6 generates reflection componentremoval data by removing the reflected wave H1 from the first directionD1, and the second reception focusing section 31 of the needle imagegeneration unit 7 performs reception focusing in the second direction D2for the reflection component removal data. Therefore, even if thereception focusing is performed in the second direction D2, which isdifferent from the first direction D1 that is the transmission directionof the ultrasonic beam, it is possible to generate a clear needle imagehaving an excellent S/N ratio without being influenced by the reflectedwave H1 from the first direction D1.

In the first embodiment described above, the acquisition of the firstelement data and the second element data is completed for all of the nscanning lines L1 to Ln in steps S1 to S5, and then the reflectioncomponent removal data is generated in step S6, and the needle image andthe tissue image are generated by performing reception focusing in stepsS7 and S8. However, the present invention is not limited thereto. Forexample, whenever the first element data and the second element data areacquired for each scanning line Li, reflection component removal datacorresponding to the scanning line Li may be generated using the firstelement data and the second element data, and a needle image and atissue image corresponding to the scanning line L1 may be generated.When a needle image and a tissue image are generated for each of all ofthe scanning lines L1 to Ln, the needle image and the tissue image arecombined.

Second Embodiment

FIG. 6 shows the internal configuration of an element data processingunit 6A used in an ultrasonic diagnostic device according to a secondembodiment. The ultrasonic diagnostic device has the same configurationas the ultrasonic diagnostic device of the first embodiment shown inFIG. 1 except that the element data processing unit 6A is used insteadof the element data processing unit 6.

The element data processing unit 6A includes an overlapping processingsection 42 connected to the element data memory 5, and a differencecalculation section 43 is connected to both the overlapping processingsection 42 and the element data memory 5 and a delay time calculationsection 44 is connected to the overlapping processing section 42. Thedifference calculation section 43 is connected to the second receptionfocusing section 31 of the needle image generation unit 7.

The overlapping processing section 42 performs overlapping processingfor overlapping a predetermined number of pieces of element data, whichare generated by the reception unit 3 corresponding to a predeterminednumber of consecutive elements of the probe 1, with each other by phasematching. The difference calculation section 43 generates reflectioncomponent removal data by taking the difference between theoverlapping-processed data generated by the overlapping processingsection 42 and the element data stored in the element data memory 5.

The delay time calculation section 44 calculates a delay time betweenthe pieces of element data required for the overlapping processing inthe overlapping processing section 42.

In the overlapping processing of the overlapping processing section 42,the transmission focus of the ultrasonic beam is regarded as a virtualsound source, a delay difference between the arrival times of reflectionpoints in respective scanning lines is calculated from the geometricpropagation length from the sound source to each reflection point, andthe signal on each scanning line is emphasized by adding up the piecesof element data of the plurality of scanning lines by correcting thedelay difference.

Here, the overlapping processing will be described with reference toFIG. 7.

It is assumed that processing for overlapping three consecutive piecesof element data with each other, among five pieces of element datacorresponding to five consecutive scanning lines, is performed.

FIG. 7(a) shows a state in which five pieces of element datacorresponding to five consecutive scanning lines are displayed side byside and an ultrasonic beam is transmitted and the reflected wave isreceived. The horizontal axis of each piece of element data indicates anelement that receives a reflected wave, and is displayed with a centralelement of the transmission opening of the ultrasonic beam in each pieceof element data at the center. The vertical axis indicates a receivingtime.

Among the five pieces of element data, in the central piece of elementdata, a reflection point is present immediately below the centralelement of the opening, and the reflected wave from the reflection pointis received. That is, the reflected wave is a true signal, and thecentral element data indicates a true signal.

For the two pieces of element data displayed on both sides of thecentral piece of element data, no reflection point is presentimmediately below the central element of the transmission opening.However, due to the spread of the transmitted ultrasonic beam, areflected wave generated by emitting an ultrasonic beam to thereflection point present immediately below the central element in thecentral piece of element data, that is, a ghost signal, is reflected.Since the propagation time of the ultrasonic wave to the reflectionpoint increases as a distance from the true signal increases, thereceiving time of the ghost signal is delayed from that of the truesignal.

In addition, the receiving element that receives the reflected wave fromthe reflection point first is an element located immediately above thereflection point. However, the horizontal axis of element data isdisplayed with the central element of the transmission opening of theultrasonic beam in the corresponding scanning line at the center, andthe transmission of an ultrasonic beam is performed by shifting thecentral element by one element for each scanning line. For this reason,in element data corresponding to each scanning line, the absoluteposition of the element is shifted by one element. That is, among thefive pieces of element data, in the central piece of element data, thereceiving element that receives the reflected wave from the reflectionpoint first is an element located at the center. However, in pieces ofelement data adjacent to both sides of the central piece of elementdata, the receiving element that receives the reflected wave from thereflection point first is shifted by one element from the central pieceof element data. Accordingly, the receiving element that receives thereflected wave from the reflection point first is shifted by one elementto the left in the piece of element data adjacent to the right side ofthe central piece of element data, and is shifted by one element to theright in the piece of element data adjacent to the left side of thecentral piece of element data. In addition, in pieces of element datalocated at both ends among the five pieces of element data, thereceiving element that receives the reflected wave from the reflectionpoint first is shifted by two elements from the central piece of elementdata. Accordingly, the receiving element that receives the reflectedwave from the reflection point first is shifted by two elements to theleft in the piece of element data located at the right end, and isshifted by two elements to the right in the piece of element datalocated at the left end. Thus, not only is the receiving time of theghost signal delayed from the receiving time of the true signal, butalso the ghost signal differs depending on the arrangement direction ofreceiving elements.

FIG. 7(b) shows an example of the delay time of the receiving time forthe central piece of element data among the five pieces of element datashown in FIG. 7(a).

In the overlapping processing section 42, using the delay time shown inFIG. 7(b), when the central element of the transmission opening is setas an observed element in the central piece of element data among thefive pieces of element data, delay time correction is performed by thenumber of pieces of element data to overlap each other (here, by thedelay time corresponding to each of three pieces of element data) withthe piece of element data corresponding to the observed element at thecenter, and the pieces of element data on both sides of the piece ofelement data corresponding to the observed element are shifted by oneelement in the horizontal direction so that the absolute position of thecentral element of the transmission opening in the piece of element datacorresponding to the observed element is the same, thereby overlappingthe three pieces of element data with each other. That is, the threepieces of element data are made to overlap each other by phase matching.As a result, a piece of overlapping-processed data corresponding to theelement data corresponding to the observed element is generated.

The overlapping-processed data obtained as described above is shown inFIG. 7(c).

Among the five pieces of element data shown in FIG. 7(a), the centralpiece of element data is the element data of a true signal. Therefore,when phase matching is performed by performing delay time correction andhorizontal shift for the pieces of element data adjacent to both sidesof the central piece of element data, the three pieces of element dataoverlap each other at a high brightness position as shown in FIG. 7(c).Accordingly, overlapping-processed data having a high brightness valueis obtained by adding up the three pieces of element data. In addition,even if an average value is calculated by averaging the three pieces ofelement data, it is possible to obtain the clear overlapping-processeddata in which the brightness is emphasized.

In contrast, FIG. 7(d) shows an example in which there are five piecesof element data as in FIG. 7(a) but element data adjacent to the leftside of the central piece of element data, that is, a central element ofthe transmission opening corresponding to the ghost signal is set as anobserved element.

FIG. 7(e) shows an example of the delay time of the receiving time forthe central piece of element data among the five pieces of element datashown in FIG. 7(d), and this is the same as the delay time of thereceiving time shown in FIG. 7(b). That is, since the element data inFIG. 7(a) and the element data in FIG. 7(d) are the same, the delay timeof the receiving time for the central piece of element data among thefive pieces of element data is the same.

In the overlapping processing section 42, using the delay time shown inFIG. 7(e), delay time correction is performed by the number of pieces ofelement data to overlap each other (here, by the delay timecorresponding to each of three pieces of element data) with the piece ofelement data corresponding to the observed element at the center, andthe pieces of element data on both sides of the piece of element datacorresponding to the observed element are shifted by one element in thehorizontal direction so that the absolute position of the centralelement of the transmission opening in the piece of element datacorresponding to the observed element is the same, thereby overlappingthe three pieces of element data with each other. That is, the threepieces of element data are made to overlap each other by phase matching.As a result, a piece of overlapping-processed data corresponding to theelement data corresponding to the observed element is generated.

The overlapping-processed data of the element data corresponding to theobserved element that has been obtained as described above is shown inFIG. 7(f).

The element data corresponding to the observed element shown in FIG.7(d) is element data of the ghost signal. Accordingly, even if delaytime correction and horizontal shift are performed for element dataadjacent to both sides of the element data, three pieces of element datado not overlap each other since the phases do not match each other asshown in FIG. 7(f). For this reason, even if the three pieces of elementdata are added up, signals having inverted phases or the like arenegated since the phases do not match each other. Accordingly, the sumvalue is not increased. In addition, an average value obtained byaveraging the three pieces of element data indicates a small value.

When the same delay time correction and horizontal shift are performedfor five pieces of element data with the central element of thetransmission opening as an observed element and three consecutive piecesof element data are made to overlap each other, an overlapping stateshown in FIG. 7(g) is obtained. FIG. 7(h) shows a result of, forexample, addition processing or averaging processing as overlappingprocessing that has been performed for these pieces of element data.

As shown in FIG. 7(h), in the central piece of element data indicatingthe true signal, overlapping-processed data having a high brightnessvalue is generated. In four pieces of element data indicating the ghostsignal that are located on both sides of the central piece of elementdata, the signals are negated since the pieces of element data havingphases that do not match each other are added up or averaged. For thisreason, the overlapping-processed data corresponding to the four piecesof element data has a smaller value than the overlapping-processed dataof the true signal having a high-brightness value at the center.

Accordingly, by performing overlapping processing in the overlappingprocessing section 42, the influence of the element data of the ghostsignal on the element data of the true signal can be negligibly reduced.

In the same manner as in the first embodiment, by forming a transmissionfocus at a predetermined depth in the first direction D1 that is thenormal direction of the element surface of the probe 1, transmitting anultrasonic beam toward the first direction D1 using the transmissionunit 2, and receiving the reflected wave in each element of the probe 1,element data shown in FIG. 8(A) is obtained. The reflected wave HI fromthe first direction D1 and the reflected wave H2 from the needle N areincluded in the element data.

Here, the reflected wave H1 from the first direction D1 can be regardedas a true signal obtained by receiving the reflected wave from thereflection point on each scanning line, and the reflected wave H2 fromthe needle N can be regarded as a ghost signal that is reflected by thespread of the transmitted ultrasonic beam.

Therefore, by making the overlapping processing section 42 performoverlapping processing for the element data stored in the element datamemory 5 so that the influence of the reflected wave H2 from the needleN can be negligibly reduced as shown in FIG. 8(B), it is possible togenerate overlapping-processed data in which the reflected wave H1 fromthe first direction D1 is emphasized.

Therefore, by taking the difference between the element data stored inthe element data memory 5 and the overlapping-processed data generatedby the overlapping processing section 42 using the differencecalculation section 43, reflection component removal data in which thereflected wave H1 from the first direction D1 has been removed whileleaving the reflected wave H2 from the needle N is generated as shown inFIG. 8(C).

By performing reception focusing in the second direction D2 for thereflection component removal data, it is possible to generate a needleimage having an excellent S/N ratio without being influenced by thereflected wave H1 from the first direction D1.

Next, an operation in the second embodiment will be described withreference to the flowchart shown in FIG. 9.

First, in step S11, for each scanning line, transmission focusing isperformed on a transmission focus at a predetermined depth in the normaldirection of the element surface of the probe 1 that is the firstdirection D1, thereby acquiring a reception signal. As a result, elementdata is acquired by the reception unit 3. Similarly, element data forall scanning lines is acquired, and is stored in the element data memory5.

Then, in step S12, for the element data stored in the element datamemory 5, overlapping processing is performed by the overlappingprocessing section 42 of the element data processing unit 6A. That is,pieces of element data corresponding to a predetermined number ofconsecutive scanning lines are made to overlap each other by phasematching, so that overlapping-processed data is generated. In this case,by setting the predetermined number of scanning lines, for which piecesof element data are made to overlap each other, to, for example, about10, it is possible to generate overlapping-processed data in which thereflected wave H2 from the needle N is not emphasized while emphasizingthe reflected wave H1 generated from the first direction D1.

In addition, the delay time between the pieces of element data requiredfor overlapping processing is calculated by the delay time calculationsection 44 of the element data processing unit 6A.

Then, in step S13, a difference between the element data stored in theelement data memory 5 and the overlapping-processed data generated bythe overlapping processing section 42 is generated by the differencecalculation section 43 of the element data processing unit 6A, so thatreflection component removal data in which the reflected wave H1 fromthe first direction D1 has been removed while leaving the reflected waveH2 from the needle N is generated.

In this case, the difference calculation section 43 may calculate thedifference after giving a weighting to either the element data stored inthe element data memory 5 or the overlapping-processed data generated bythe overlapping processing section 42 or to both the element data storedin the element data memory 5 and the overlapping-processed datagenerated by the overlapping processing section 42. In addition, it isalso possible to change the value of the weighting and the calculationmethod depending on the depth.

Then, in step S14, the needle image generation unit 7 generates a B-modeimage signal for needle imaging by performing reception focusing in adirection perpendicular to the needle N, which is the second directionD2, for the reflection component removal data generated by thedifference calculation section 43, and the B-mode image signal forneedle images is stored in the image memory 33.

Then, in step S15, the tissue image generation unit 4 generates a B-modeimage signal for tissue imaging by performing reception focusing in thenormal direction of the element surface of the probe 1, which is thefirst direction D1, for the element data stored in the element datamemory 5, and the B-mode image signal for tissue images is stored in theimage memory 23.

Then, in step S16, the B-mode image signal of the tissue image stored inthe image memory 23 of the tissue image generation unit 4 and the B-modeimage signal of the needle image stored in the image memory 33 of theneedle image generation unit 7 are raster-converted by the imagecombination unit 8, and are combined with each other after various kindsof image processing are performed. As a result, a B-mode image signal ofthe display image is generated.

The B-mode image signal of the display image is output to the displaycontrol unit 9 from the image combination unit 8, and an ultrasonicimage in which the tissue image and the needle image are combined isdisplayed on the display unit 10.

The overlapping-processed data in which the reflected wave H1 generatedfrom the first direction Dl is emphasized is generated by theoverlapping processing section 42 of the element data processing unit6A, the reflection component removal data in which the reflected wave HIfrom the first direction Dl has been removed is generated by thedifference calculation section 43, and reception focusing is performedin the second direction D2 for the reflection component removal data bythe second reception focusing section 31 of the needle image generationunit 7. Therefore, even if the reception focusing is performed in thesecond direction D2 different from the first direction D1 that is thetransmission direction of the ultrasonic beam, it is possible togenerate a clear needle image with an excellent S/N ratio without beinginfluenced by the reflected wave H1 from the first direction D1.

In the second embodiment described above, the tissue image generationunit 4 generates a B-mode image signal for tissue imaging by performingreception focusing in the first direction D1 for the element data storedin the element data memory 5. However, the present invention is notlimited thereto. For example, the tissue image generation unit 4 may beconfigured to generate a B-mode image signal for tissue imaging byperforming reception focusing in the first direction D1 for theoverlapping-processed data which is generated by the overlappingprocessing section 42 of the element data processing unit 6A and inwhich the reflected wave H1 generated from the first direction D1 isemphasized.

In step S12, a predetermined number of consecutive scanning lines areset as scanning lines to be subjected to overlapping processing by theoverlapping processing section 42 of the element data processing unit6A. However, the scanning lines to be subjected to overlappingprocessing by the overlapping processing section 42 of the element dataprocessing unit 6A do not necessarily need to be consecutive, or may notbe consecutive as long as these are scanning lines in a range wherepieces of element data overlap each other.

Third Embodiment

FIG. 10 shows the internal configuration of an element data processingunit 6B used in an ultrasonic diagnostic device according to a thirdembodiment. The ultrasonic diagnostic device has the same configurationas the ultrasonic diagnostic device of the first embodiment shown inFIG. 1 except that the element data processing unit 6B is used insteadof the element data processing unit 6.

The element data processing unit 6B includes a simulation processingsection 45 connected to the element data memory 5. A differencecalculation section 46 is connected to the simulation processing section45, and the difference calculation section 46 is connected to the secondreception focusing section 31 of the needle image generation unit 7.

The simulation processing section 45 generates simulation dataindicating the reflected wave H1 generated from the first direction D1by performing simulation processing, and the difference calculationsection 46 generates reflection component removal data by taking thedifference between the simulation data generated by the simulationprocessing section 45 and the element data stored in the element datamemory 5.

The simulation processing in the simulation processing section 45 is forgenerating the reflected wave from the reflection point located on eachscanning line by simulation, and the operation is shown in the flowchartof FIG. 11.

In addition, it is assumed that element data is acquired in advance byactually transmitting and receiving ultrasonic beams in the ultrasonicdiagnostic device of the third embodiment.

In step S21, measurement conditions when actually acquiring elementdata, such as a focus position and the number of pieces of data, isinput.

Then, in step S22, a sound speed value required for the operation ofsimulation is input.

Then, in step S23, the operation of simulation is executed using themeasurement conditions input in step S21 and the sound speed value inputin step S22, thereby generating a reflected wave.

After the reflected wave is generated as described above, in subsequentstep S24, a difference between the generated reflected wave and theelement data acquired in advance by actually transmitting and receivingultrasonic beams is calculated, and it is determined whether or not thedifference is equal to or less than the allowable value set in advance.

When it is determined that the difference exceeds the allowable value instep S24, the process proceeds to step S25 to update the sound speedvalue to a new value. Then, the process returns to step S23 in which areflected wave is generated by performing simulation again using theupdated sound speed value. Then, in step S24, a difference between thenew reflected wave and the element data acquired in advance iscalculated, and it is determined whether or not the difference is equalto or less than the allowable value.

Since the shape of the reflected wave generated by the simulationchanges according to the sound speed value to be used, steps S23 to S25are repeated while updating the sound speed value until the differencebetween the reflected wave and the element data becomes within theallowable value.

When it is determined that the difference between the reflected wave andthe element data becomes within the allowable value in step S24, thereflected wave at this time is set as simulation data generated by thesimulation processing, and the simulation processing is ended.

As the sound speed value, it is possible to generate a reflected wave bysimulation by inputting a fixed value that does not depend on the depth.Alternatively, a reflected wave by simulation may be generated for eachdepth by inputting a different sound speed value for each depth.

In the same manner as in the first embodiment, by forming a transmissionfocus at a predetermined depth in the first direction D1 that is thenormal direction of the element surface of the probe 1, transmitting anultrasonic beam toward the first direction D1 using the transmissionunit 2, and receiving the reflected wave in each element of the probe 1,element data shown in FIG. 12(A) is obtained. The reflected wave H1 fromthe first direction D1 and the reflected wave H2 from the needle N areincluded in the element data.

Since the simulation processing in the simulation processing section 45is for generating the reflected wave from the reflection point locatedon each scanning line by simulation, simulation data including thereflected wave H1 from the first direction D1 can be generated as shownin FIG. 12(B) by performing simulation processing.

Therefore, by taking the difference between the element data stored inthe element data memory 5 and the simulation data generated by thesimulation processing section 45 using the difference calculationsection 46, reflection component removal data in which the reflectedwave H1 from the first direction D1 has been removed while leaving thereflected wave H2 from the needle N is generated as shown in FIG. 12(C).

By performing reception focusing in the second direction D2 for thereflection component removal data, it is possible to generate a needleimage having an excellent S/N ratio without being influenced by thereflected wave H1 from the first direction Dl.

Next, an operation in the third embodiment will be described withreference to the flowchart shown in FIG. 13. In the flowchart shown inFIG. 13, steps S32 and S33 are executed instead of steps S12 and S13 inthe flowchart of the second embodiment shown in FIG. 9, and other stepsare the same as those in the flowchart shown in FIG. 9.

First, in step S11, for each scanning line, transmission focusing isperformed on a transmission focus at a predetermined depth in the normaldirection of the element surface of the probe 1 that is the firstdirection D1, thereby acquiring a reception signal. As a result, elementdata is acquired by the reception unit 3. Similarly, element data forall scanning lines is acquired, and is stored in the element data memory5.

Then, in step S32, simulation data indicating the reflected wave H1generated from the first direction Dl is generated by the simulationprocessing section 45 of the element data processing unit 6B.

Then, in step S33, a difference between the element data stored in theelement data memory 5 and the simulation data generated by thesimulation processing section 45 is generated by the differencecalculation section 46 of the element data processing unit 6B, so thatreflection component removal data in which the reflected wave H1 fromthe first direction D1 has been removed while leaving the reflected waveH2 from the needle N is generated. In this case, in the differencecalculation, either the element data or the simulation data or both theelement data and the simulation data may be weighted to perform adifference calculation.

Then, in step S14, the needle image generation unit 7 generates a B-modeimage signal for needle imaging by performing reception focusing in adirection perpendicular to the needle N, which is the second directionD2, for the reflection component removal data generated by thedifference calculation section 46, and the B-mode image signal forneedle images is stored in the image memory 33.

Then, in step S15, the tissue image generation unit 4 generates a B-modeimage signal for tissue imaging by performing reception focusing in thenormal direction of the element surface of the probe 1, which is thefirst direction D1, for the element data stored in the element datamemory 5, and the B-mode image signal for tissue images is stored in theimage memory 23.

Then, in step S16, the B-mode image signal of the tissue image stored inthe image memory 23 of the tissue image generation unit 4 and the B-modeimage signal of the needle image stored in the image memory 33 of theneedle image generation unit 7 are raster-converted by the imagecombination unit 8, and are combined with each other after various kindsof image processing are performed. As a result, a B-mode image signal ofthe display image is generated.

The B-mode image signal of the display image is output to the displaycontrol unit 9 from the image combination unit 8, and an ultrasonicimage in which the tissue image and the needle image are combined isdisplayed on the display unit 10.

The simulation data indicating the reflected wave H1 generated from thefirst direction D1 is generated by the simulation processing section 45of the element data processing unit 6B, the reflection component removaldata in which the reflected wave H1 from the first direction D1 has beenremoved is generated by the difference calculation section 46, andreception focusing is performed in the second direction D2 for thereflection component removal data by the second reception focusingsection 31 of the needle image generation unit 7. Therefore, even if thereception focusing is performed in the second direction D2 differentfrom the first direction D1 that is the transmission direction of theultrasonic beam, it is possible to generate a clear needle image with anexcellent S/N ratio without being influenced by the reflected wave HIfrom the first direction D1.

Although the B-mode image signal of the tissue image and the B-modeimage signal of the needle image are combined by the image combinationunit 8 and the result is displayed on the display unit 10 in the firstto third embodiments described above, reflection component removal dataobtained by removing the reflected wave H1 from the first direction D1may be combined with the B-mode image, which is a tissue image, as it isand the result is displayed.

The needle image can be displayed in various kinds of display formats,such as a binary image and color display.

In addition, only the needle image may be displayed on the display unit10 without combining the needle image with the tissue image. Also inthis case, it is possible to use various kinds of display formats, suchas a B-mode image, reflection component removal data itself, a binaryimage, and color display.

EXPLANATION OF REFERENCES

1: probe

2: transmission unit

3: reception unit

4: tissue image generation unit

5: element data memory

6, 6A, 6B: element data processing unit

7: needle image generation unit

8: image combination unit

9: display control unit

10: display unit

11: control unit

12: operation unit

13: storage unit

21: first reception focusing section

22, 32: detection processing section

23, 33: image memory

31: second reception focusing section

41, 43, 46: difference calculation section

42: overlapping processing section

44: delay time calculation section

45: simulation processing section

D1: first direction

D2: second direction

F1: first transmission focus

F2: second transmission focus

C: reflection point

R0, R1, R2: path

RA: reception opening

T: element located at center

N: needle

θ: insertion angle

S: subject

What is claimed is:
 1. An ultrasonic diagnostic device, comprising: aprobe including a plurality of elements that are arranged; atransmission unit that transmits an ultrasonic beam by performingtransmission focusing in a first direction from the plurality ofelements of the probe; a reception unit that generates element data byprocessing reception signals output from the plurality of elements ofthe probe that has received an ultrasonic echo generated by theultrasonic beam transmitted from the transmission unit; an element dataprocessing unit that generates reflection component removal data byremoving a reflection component generated from the first direction fromthe element data; an image generation unit that generates an ultrasonicimage by performing reception focusing for the element data; and acontrol unit that controls the image generation unit to generate animage signal along a second direction different from the first directionby performing reception focusing in the second direction for thereflection component removal data generated by the element dataprocessing unit.
 2. The ultrasonic diagnostic device according to claim1, wherein the transmission unit forms at least two focuses at differentpositions in the first direction to sequentially transmit a plurality ofultrasonic beams, and the element data processing unit generates thereflection component removal data from a plurality of pieces of elementdata generated by the reception unit corresponding to the plurality ofultrasonic beams.
 3. The ultrasonic diagnostic device according to claim2, wherein the element data processing unit generates the reflectioncomponent removal data by taking a difference between the plurality ofpieces of element data.
 4. The ultrasonic diagnostic device according toclaim 3, wherein, when taking a difference between the plurality ofpieces of element data, the element data processing unit takes adifference after giving weighting to any one of the plurality of piecesof element data or to the plurality of pieces of element data.
 5. Theultrasonic diagnostic device according to claim 1, wherein the elementdata processing unit generates overlapping-processed data in which areflection component generated from the first direction is emphasized byoverlapping a predetermined number of pieces of element data generatedby the reception unit with each other by phase matching corresponding tothe predetermined number of consecutive scanning lines, and generatesthe reflection component removal data using the overlapping-processeddata.
 6. The ultrasonic diagnostic device according to claim 5, whereinthe element data processing unit generates the reflection componentremoval data by taking a difference between the element data by theplurality of elements generated by the reception unit and theoverlapping-processed data.
 7. The ultrasonic diagnostic deviceaccording to claim 6, wherein, when taking a difference between theelement data by the plurality of elements generated by the receptionunit and the overlapping-processed data, the element data processingunit takes a difference after giving weighting to either the elementdata by the plurality of elements generated by the reception unit or theoverlapping-processed data or to both the element data by the pluralityof elements generated by the reception unit and theoverlapping-processed data.
 8. The ultrasonic diagnostic deviceaccording to claim 1, wherein the element data processing unit generatessimulation data indicating a reflected wave generated from the firstdirection by simulation, and generates the reflection component removaldata using the simulation data.
 9. The ultrasonic diagnostic deviceaccording to claim 8, wherein the element data processing unit generatesthe reflection component removal data by taking a difference between theelement data by the plurality of elements generated by the receptionunit and the simulation data.
 10. The ultrasonic diagnostic deviceaccording to claim 9, wherein, when taking a difference between theelement data by the plurality of elements generated by the receptionunit and the simulation data, the element data processing unit takes adifference after giving a weighting to either the element data by theplurality of elements generated by the reception unit or the simulationdata or to both the element data by the plurality elements generated bythe reception unit and the simulation data.
 11. The ultrasonicdiagnostic device according to claim 1, wherein the image generationunit includes: a tissue image generation section that generates an imagesignal for tissue imaging along the first direction by performingreception focusing in the first direction for the element data; and aneedle image generation section that generates an image signal forneedle imaging along the second direction by performing receptionfocusing in the second direction for the reflection component removaldata.
 12. The ultrasonic diagnostic device according to claim 11,further comprising: an image combination unit that combines the imagesignal for tissue imaging generated by the tissue image generationsection and the image signal for needle imaging obtained by the needleimage generation section.
 13. The ultrasonic diagnostic device accordingto claim 12, further comprising: a display unit that displays an imagesignal obtained by a combination of the image combination unit.
 14. Theultrasonic diagnostic device according to claim 1, further comprising: adisplay unit that displays an ultrasonic image generated by the imagegeneration unit.
 15. An ultrasonic image generation method, comprising:transmitting an ultrasonic beam by performing transmission focusing in afirst direction from a plurality of elements of a probe; generatingelement data by processing reception signals output from the pluralityof elements of the probe that has received an ultrasonic echo generatedby the ultrasonic beam; generating reflection component removal data byremoving a reflection component generated from the first direction fromthe element data; and generating an ultrasonic image along a seconddirection different from the first direction by performing receptionfocusing in the second direction for the reflection component removaldata.